This invention relates to well port structures and more specifically to a port valve apparatus having a three position sleeve valve and an opening tool therefore.
Sleeve valve devices have been used in oil wells whenever it is desirable to control fluid flow between the interior and exterior of the well tubing. For instance, such devices are used in wells with a plurality of longitudinally spaced geological strata in which it is desired to have only one stratum in communication with the interior of the well tubing at any given time. One sleeve valve device is located at each stratum and opening and closing tools are lowered into the well tubing to manipulate the various valves. Each sleeve valve usually comprises an outer tubular body having a fluid port in the wall thereof and within the bore of the tubular body a sleeve valve in longitudinally slideable engagement with the surface of the bore, the sleeve having a fluid port in the wall thereof. Depending on whether the valve is to be opened or closed, the appropriate tool is lowered into the well to move the sleeve longitudinally to place the fluid ports in register or to move them out of register.
A problem was encountered in opening such sleeve valves when the ambient pressure in the geological stratum was much higher than in the well tubing. The sudden fluid communication resulting from the opening of the sleeve valve could result in the opening tool being blown back up the pipe with resultant damage. The solution to this problem was to equalize the pressure more gradually between the inside of the well tubing and the geological stratum by the use of a three position sleeve valve with an intermediate position between the closed and opened positions at which restricted flow orifices in the sleeve valve are in communication with the port of the outer tubular body. First the sleeve is shifting to the intermediate position for the pressure to equalize after which the sleeve is shifted to the open position for normal fluid flow.
This in turn enhanced the need, also present with the two position valve structure, for an opening tool which could accurately shift the sleeve valve between positions with a positive throw action which would engage the sleeve valve at one position and shift it to a second position disengaging the sleeve valve exactly when the second position is reached.